Table 5.
Comparison between ASTM D1500 standard, and estimated color index using Equations (1) and (2).
| Sample | ASTM D1500 | Estimated CI | Difference in CI | RMSE | |
|---|---|---|---|---|---|
| Equation (1) CI405 (R2 = 0.99170) |
S1 | 0.5 | 0.55 | 0.05 | 0.2229 |
| S2 | 1.0 | 0.99 | −0.01 | ||
| S3 | 1.5 | 1.39 | −0.11 | ||
| S4 | 2.0 | 1.97 | −0.03 | ||
| S5 | 2.5 | 2.52 | 0.02 | ||
| S6 | 3.0 | 3.25 | 0.25 | ||
| S7 | 5.0 | 4.50 | −0.50 | ||
| S8 | 5.5 | 5.87 | 0.37 | ||
| S9 | 6.5 | 6.26 | −0.24 | ||
| S10 | 7.0 | 7.15 | 0.15 | ||
| S11 | 7.5 | 7.55 | 0.05 | ||
| Equation (2) CI450 (R2 = 0.97200) |
S1 | 0.5 | 0.97 | 0.47 | 0.4129 |
| S2 | 1.0 | 1.34 | 0.34 | ||
| S3 | 1.5 | 1.60 | 0.10 | ||
| S4 | 2.0 | 1.86 | −0.14 | ||
| S5 | 2.5 | 2.25 | −0.25 | ||
| S6 | 3.0 | 2.52 | −0.48 | ||
| S7 | 5.0 | 4.46 | −0.54 | ||
| S8 | 5.5 | 5.33 | −0.17 | ||
| S9 | 6.5 | 6.13 | −0.37 | ||
| S10 | 7.0 | 7.17 | 0.17 | ||
| S11 | 7.5 | 8.36 | 0.86 |
CI—Color index.